1. Field of the Invention
This invention relates to a ratchet wrench, and more particularly to a ratchet wrench having a direction switching device for switching the rotational direction of a driving head.
2. Description of the Related Art
Referring to FIG. 1, a ratchet wrench 1 disclosed in Taiwanese patent No. M417233 includes a body 11, a driving wheel 13 disposed pivotally on a front end portion of the body 11 for driving rotation of a driving head 12, two push rods 14 movable toward or away from the driving wheel 13, a pawl member 15 driven by the push rods 14 to swing, and a rotatable member 16 sleeved rotatably on the body 11. The rotatable member 16 has an inner surface formed with a plurality of concave portions 161 and a plurality of convex portions 162 arranged alternately with the concave portions 161.
Upon rotation of the rotatable member 16, one of the concave portions 161 is brought into alignment with one of the push rods 14 to form a space between the one of the push rods 14 and the rotatable member 16 so as to allow the one of the push rods 14 to be biased by a spring unit (not shown) away from the pawl member 15, and one of the convex portions 162 contacts and pushes the other of the push rods 14 to mesh with the driving wheel 13, thereby limiting the driving head 12 to rotate in a corresponding direction.
However, when one of the push rods 14 moves rearwardly to contact one of the concave portions 161, the other of the push rods 14 is moved forwardly by one of the convex portions 162 to rotate the pawl member 15 to mesh with the driving wheel 13. As such, when no external force is applied to the rotatable member 16, the pawl member 15 is kept in contact with the driving wheel 13 to create a frictional resistance to smooth rotation of the driving head 12.